Virtual Network Computing, better known as VNC, is something most geeks have stumbled across and used during their time sat in front of a PC. It allows for the control of other, remote machines by transmitting the keyboard and mouse input from one to the other while showing the user the output from the other machine.

VNC offers up another mode, however, which allows the output of one machine to be displayed on another for others to watch rather than interact with. It’s called listen mode, and computer programmer Rob Hague has managed to get it working on the Raspberry Pi $25 PC using VNC Viewer.

Being able to just watch what is happening on the screen in front of you may not sound too exciting, but then you have to remember Raspberry Pi is first and foremost aimed at the education sector. Using this VNC solution you could easily have a teacher demonstrating something on a PC with all the students viewing it through their Raspberry Pi rather than straining to see a projection at the front of the class.

With my limited knowledge of VNC I assume that is possible, but even if it isn’t the system still allows one-on-one screen viewing and switching with each student if they need to see how something is done. It also works with any OS that can run VNC, meaning Windows, Mac, and Linux hosts work.

Hague achieved the demonstration you see in the video below by getting TightVNC loaded and working on the Raspberry Pi. For the Mac, he used Vine Server as the built-in solution OS X Lion relies on “doesn’t support reverse connections.” Both pieces of software are free to use, meaning this will hopefully work for everyone from the day the $25 PC ships.

As you can see, there is some lag, but it’s minor. Also, it’s being run on an alpha board, not the final hardware, so performance is sure to improve upon release.